1. Field of the Invention
The present invention relates generally to container security and, more particularly, to a shipping container security system to provide a high degree of confidence regarding the content and security of the container through imaging technology.
2. Background of the Invention
In today's security conscious transportation environment, there is a strong need to cost-effectively and accurately monitor the contents of containerized shipments. This need exist both in the United States and abroad.
Despite the strong need, until recently few solutions, if any, have been able to provide the protection and accuracy needed to suit the transportation industry and the government agencies charged with monitoring shipments. This lack of an acceptable solution is due to many factors which complicate interstate and international shipping. Shipping containers are used to transport most of the commerce entering, leaving, and transiting or moving within the United States. It is estimated that there are over 6 million containers moving in global commerce. Shipping containers have revolutionized the transportation of goods by greatly reducing the number of times goods must be loaded and unloaded during transport. However, at the same time, this same advantage has created a major problem in that it is very difficult to monitor and track the contents of each container during transport.
Beyond their basic construction, monitoring the content of shipping containers is also difficult because these containers are carried through numerous transit points and depots all over the world and it is impractical to stop and check the contents of each container individually at each point of transit. Dealing with this problem, the U.S. Customs Service estimates it can inspect just 5% of the 6 million containers entering and reentering the U.S. each year. Accordingly, agencies such as the United States Customs Service are seeking improved ways to achieve cargo container security and integrity upon arrival at the ports of entry of the United States.
A container security system must have an array of sensors to monitor many different tampering events. Typical sensors may be acoustic or vibration, temperature, light, and GPS location. Other more sophisticated sensors may include infrared or heat, chemical, biological, or even radiation sensors. In spite of the number and sophistication of these sensors, the basic question of what is actually happening in and around a container may not be exactly ascertained without a visual image.
As solid state imaging devices become ubiquitous, the cost of these devices is becoming so low that they may now be used for many applications where only a few years ago the expense was entirely prohibitive. CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor) image sensors are two different technologies for capturing images digitally. Each has unique strengths and weaknesses giving advantages in different applications. One interesting bi-product of many of these devices is their ability to operate below the visible spectrum into the infrared (IR) region as well. This can be readily seen by holding up a cell phone camera to an IR TV remote control and seeing the LED flash in the camera when it cannot be seen by the naked eye.
One of the key advantages of an image capture system is to allow images to be sent to a remote location or monitoring station for examination action. However, due to the power limitations of container monitoring systems, the communication channels are frequency narrowband and in the range of a few bytes per day at the low end to a few thousand bit per second at the high end. For this reason it may be useful to apply image compression to the captured images prior to transmission.